This proposed research will seek to define the role of T lymphocyte subpopulations in B lymphocytes, passively administered isotype specific antibody and the secretory IgA immune system in the establishment of experimental periodontal disease in rats infected with Actinobacillus actinomycetemcomitans (Aa). We have proposed to explore the nature of these roles with a series of experiments in which adoptive transfer of cells or passive transfer of antibodies will be utilized. The research has three major directions for study: (1) The effects of adoptive transfer of selected cell populations on experimental periodontal bone loss in rats, (2) the effect of SIgA immunity on experimental periodontal bone loss in rats, and (3) the effect of passive transfer of immune IgG or IgA antibody to Aa on experimental periodontal bone loss in rats. A combination of immunologic techniques will be employed in these investigations. Sensitization will be determined by lymphocyte blastogenesis. Cells will be isolated by a variety of panning procedures. Specific T cell subpopulations will be identified with monoclonal reagents and antigen specific T cell subpopulations will be propagated and cloned. Antibodies will be measured by an ELISA procedure. Several methods of interfering with periodontal disease are proposed.